1. Field of the Invention
The subject invention relates to an improved electronic medication delivery pen.
2. Description of Related Art
Home diabetes therapy requires the patient to carry out a prescribed regimen that involves self-testing blood glucose levels and administering an appropriate dose of insulin. Insulin has traditionally been injected by a hypodermic syringe, which suffers from numerous drawbacks. For example, syringes are not preloaded with medication, requiring the user to carry a separate medical vial. Syringes also require a degree of dexterity and sufficient visual acuity on the part of the patient to line up the needle of the syringe with the rubber septum on the medical vial and to ensure that the syringe is loaded with the proper dosage. As a result, unintentional needle pricks commonly occur.
To overcome the drawbacks of syringes, medication delivery pens have been developed, which facilitate the self-administration of medication such as insulin. Such delivery pens use prepackaged insulin and may be used repeatedly until the medication is exhausted. Mechanical and electronic pens are available. Electronic pens incorporate electronic circuitry that sets and/or indicates the appropriate dosage of insulin and stores data for subsequent downloading such as the time, date, amount of medication injected, etc.
While electronic pens that mechanically simplify the device have been proposed, it has been found that there remains a need for additional features and improvements that further utilize the electronic capabilities of the pen. For example, it would be desirable to automatically determine the amount of insulin that remains in a cartridge from which one or more dosages of medication have been delivered. Likewise, it would be desirable to automatically determine the size of the cartridge that is installed in the pen as well as the type of medication contained in the cartridge, thus allowing many different types of cartridges to be used in a single pen while reducing the likelihood of user error resulting from misidentifying the cartridge or manually entering incorrect information into the pen.
The subject invention relates to an electronic medication delivery pen in which the value of different modes such as time and date modes are changed by the actuator when the actuator is disengaged from the drive mechanism of the pen.
In accordance with the present invention, a medication delivery pen includes a housing having opposing proximal and distal ends. An actuator is disposed in the proximal end of the housing for setting and administering a dosage of medication. The pen also includes a medication-containing cartridge assembly having a cartridge with a pierceably sealed distal end, an open proximal end removably attachable to the distal end of the housing, and a piston in sliding fluid tight engagement within the cartridge. A drive mechanism is coupled between the actuator and the cartridge to exert an axial force on the piston to inject the set dosage of medication. The actuator triggers the drive mechanism to administer the injection of medication held in the cartridge. A processor is coupled to the actuator to determine a value equal to the dosage set by the actuator. A memory device is coupled to the processor to store at least the dosage value determined by the processor. A display is located on the housing and coupled to the processor for displaying information provided by the processor. In a first state the actuator engages with the drive mechanism to deliver the medication and in a second state is disengaged from the drive mechanism. In its second state, the actuator serves as a user adjustable input for changing and setting mode parameters of at least one preselected mode of the pen.
In some embodiments of the invention the actuator includes a rotatable knob for setting the dosage of medication. The rotatable knob also serves as the user adjustable input when the actuator is in the second state. The rotatable knob may be rotated when in the second state for changing and setting the mode parameters. Other user-inputs that may be provided include a user-activatable mode button located on the housing for selecting the preselected mode of the pen from among multiple modes such as a time and date mode, and an eject button for selectively alternating between the first and second states of the actuator.
In accordance with one aspect of the invention, the medication delivery pen also includes a sensor coupled to the processor for detecting status information pertaining to the drive mechanism to determine a quantity of medication remaining in the cartridge. Such status information may include, for example, the linear position of a leadscrew that forms part of the drive mechanism.
In accordance with another aspect of the invention, the cartridge has an encoded portion which identifies at least one characteristic of the cartridge. A sensor is coupled to the processor for detecting the encoded portion of the cartridge so that the processor can determine the corresponding characteristic of the cartridge. The characteristic of the cartridge that is determined from the encoded portion may be the type of medication in the cartridge or the size of the cartridge, for example. The encoded portion of the cartridge may be a color code.